The present invention relates to vehicle wiring, and more specifically to reducing usage of copper metal in trailer lighting systems.
Vehicle lighting systems required wiring to supply current to the individual lamps within the vehicle. In the case of large tractor trailers in Class 8, the wiring harnesses typically employ large diameter copper conductors which are sized to handle the high current requirements of traditional incandescent lighting. For example, typically, for a 7-Conductor cable (per SAE J1067 and J560) the ground wire is typically 8 or 10 gauge, and the other wires are typically 10 or 12 gauge, typically all being copper wire. A typical main harness, which extends from the nose box back is typically 8 to 12 gauge of copper, with typical lengths of, for example, about 35, 50, 60 or 100 feet. The prior art includes the Grote Nose-Box Jumper Harness with 10 and 12 gauge copper wire and 25 amp breakers. Due to their large diameter and high conductivity, such copper conductors will also typically draw more than 25 amps of current if a short circuit develops at the rear end of the trailer. Since most tractors include a 25 amp breakers, the tractor and trailer wiring are protected from such failure conditions.
We have discovered how to improve on the environment by using less copper, save on the cost of copper, and yet reduce risk of short circuit problems in the context of some Class 8 truck trailers.
When LED lighting is used in the trailer, the current required to run the LED lamps is much less than that of incandescent lighting. Therefore, we can take advantage by the use of, for example, smaller diameter copper conductors and/or alloys using less copper, metals or alloys using no copper, and/or other approaches, such as copper sheathing, to reduce copper usage. However, we have realized that this approach, while beneficial, can give rise to one or more disadvantages. First, the increased resistance of the smaller (or otherwise less conductive) conductor can restrict the possible short circuit current to a level which is too low to trip the 25 amp breaker in a typical tractor pulling the trailer. For example, if 20 AWG conductor is used, a short that occurs 50 feet from the trailer nose box would draw 18 amps, high enough to potentially melt the wiring insulation, but below the 25 amps required to trip the typical breaker in the tractor. Smaller conductor wiring will also typically have thinner insulation and will be less rigid. This loss of rigidity makes it harder to install the wiring during the trailer manufacturing process and increase the associated labor costs.
Thus, there is a need for improvement in this field.